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Radiation Protection > Test 2 > Flashcards

Test 2 Flashcards

1
Q

Bateman Equation

A

Ad=Ap(0)(e^(kpt)-e^(kdt))kd/(kd-kp)

Where p = parent, d = daughter. Note also that Ad(0)e^(kdt) is activity of parent over time.

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2
Q

Definition of Reference Man

A

As originally defined in ICRP 23 (but later changed in ICRP 89): 70kg, 170cm, Caucasian, living in 10~20C, and 20~30 years old.

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3
Q

Snyder-Fisher Mathematical Model

A

Used for calculating dose in other organs due to source organ emitting radioactivity. A phantom was created to represent this model.

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4
Q

Exposure, Dose, Equivalent Dose, and Effective Dose calculation

A

Dose D = exposure X * constant
Equivalent dose H = Beam Quality Q (ICRP 26) * D
or Radiation Weighting Factor Wr (ICRP 60) * D
Effective dose E = sum (Tissue Weighting Factor * H) for all tissues involved

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5
Q

ICRP 30 (~1980)

A

Includes Part 2 and addendum on Part 4: “Limits for Intakes of Radionuclides by Workers.”

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6
Q

ICRP 26 (1977)

A

This publication of ICRP introduced quality factor for ionizing radiation, introduced dose equivalent, effective dose equivalent, and set up basic internal dosimetry concepts.

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7
Q

ICRP 26 Formulation of Internal Dosimetry

A

Source and target organs concept introduced. Absorbed fraction concept introduced (absorbed energy / emitted energy). Quality factors defined for beta, alpha, neutrons, and gamma. Tissue weighting factor defined. Equivalent dose for 50 years, H50 = sum (Quality factor * dose for 50 years), defined.

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8
Q

ALI (Annual Limit on Intake)

A

Activity of nuclide taken in that would itself alone result in EFFECTIVE DOSE (not equivalent!) of 50 mSv (annual dose limit). ***UNIT: Bq/yr

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9
Q

Stochastic Limit for ALI Calculation

A

Assume 50 mSv 50-year EFFECTIVE DOSE limit to calculate ALI in Bq/yr. We can do so by dividing 50 mSv by effective dose per decay!

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10
Q

Nonstochastic Limit for ALI Calculation

A

Assume 500 mSv 50-year EQUIVALENT DOSE (H50=Wr * D) limit to calculate ALI in Bq/yr. We can do so by dividing 500 mSv by equivalent dose per decay!
NOTE: LENS OF EYE is an exception! Assume 150 mSv limit!

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11
Q

Solving for H, Equivalent dose given for 50 years

A

H = k * U * SEE, where U = # of decays, SEE = specific effective energy (equivalent dose per transformation, Wt * D / Bq), and k = constant for energy conversion

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12
Q

Specific Effective Energy Calculation

A

SEE = sum over different radiation types (Quality Q * Radioactive Yield Y * Energy Emitted E * absorbed fraction AF(T<-S) / Mass of Tissue M).
Basically, equivalent dose per decay on target organ T. May result in MeV/g.
Convert to Sv: SEE (MeV/g) * (1.6*10^-10) = SEE (Sv)

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13
Q

Quality Factors for various radiation sources (ICRP 26)?

A

Beta, gamma = 1
Fast neutron, proton = 10
Alpha, fission fragments = 20

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14
Q

Absorbed Fraction AF for SEE Calculation

A

Can be reasonably determined: AF = 1 for beta, alpha for S<-S; if target is sufficiently far away, AF =0 since beta/alpha stops in less than 1 mm in tissue.

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15
Q

formula for effective half-life given biological clearance half-life Tb and physical decay rate Tr

A

Teff = Tr * Tb / (Tr + Tb)

Note: this looks like effective mass, doesn’t it?

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16
Q

Three Mile Island 1979

A

43,000 Curies Krypton but less (15 Curies) of Iodine-131 released. 2 mrem within 50 miles of TMI to 2 mil.

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17
Q

1 mCi = ? MBq

A

37 MBq

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18
Q

Chernobyl 1986

A

Over 100 rad to 200 workers; over 400 rad to 30 workers (all dead); average of 20 rem to within 200 miles of the reactor, population of 272,800.
I-131: 17 million curies
Cs-137: 2 million curies

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19
Q

Tritium Exit Signs

A

Originally 15 Curies, self-luminating exit sign. Sold in US, still circulating.

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20
Q

Solubility in Tissue of Common Isotopes

A

Tritium: 0.02 ; Xenon: 0.1

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21
Q

How do you calculate equivalent dose rate dH/dt for people immersed in radioactive gas? Give three equations, one for external radiation due to surrounding gas, one for absorbed gas in tissue, and one for lung from inhaled gas.

A

Dose derived from activity concentration, Bq/g = (Bq/cm^3) / (g/cm^3)

External radiation: dH/dt = g(e) * k * C/p * s, where k is ratio of stopping powers in air versus in tissue k~1, C/p is activity concentration in Bq/g, and s is equivalent dose rate Sv/hr of air per Bq/g

Absorbed gas in lung: dH/dt = g(a) * [delta * C/p] * s, where delta is solubility

Air in lung: dH/dt = g(L) * C / (M/V) * s, where p is replaced with mass of lung and volume of AIR in lung

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22
Q

Xenon-133

A

Specific gamma constant: 0.15 Rcm^2/mCihr

So exposure = gamma * activity / distance^2. Biological half life 2 min, physical half life 5.27 days.

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23
Q

What is Cumulated Activity for instantaneous uptake? What is the formula for it?

A

Activity integrated over infinite time (total disintegrations)
A = Ao * 1.44 * Teff
where Teff is effective half life.

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24
Q

Find integral dose from cumulated activity.

A 
Integral dose (g*rad) = A (uCi*hr) * delta,
where delta is conversion from cumulated activity A to energy (g*rad is a unit of energy). This equation only applies if we assume all energy is absorbed by source organ.
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25
Q

What is Cumulated Activity for non-instantaneous uptake? Formula?

A

A = Ao * 1.44 * Teff * (Tue/Tu),

where Tue = Tu*Tp/(Tu+Tp). Notice how as Tu -> 0 (instantaneous uptake), Tue/Tu -> 1.

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26
Q

What is formula for delta, disintegration-to-energy conversion factor? (Used to calculate gramrad from uCihr)

A

delta = 2.13 * Y * E (gramrad/uCihr),

where Y = emission ratio (100% or less), E = energy emitted in MeV

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27
Q

Specific absorbed fraction

A

Absorbed fraction of dose released from source to target PER gram of target organ. = AF / mass of target.

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28
Q

Reciprocity theorem

A

Specific absorbed fraction is equal for source organ and target organ even if the source and target are switched. That is, AF(S<-T) / mass of source.

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29
Q

Mean Dose per Cumulated Activity, S

A

S(T<-S) * delta / m_T ].

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30
Q

MIRD Stands for?

A

Medical Internal Radiation Dose

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31
Q

ICRP vs MIRD compare and contrast

A

ICRP concerned with hereditary effects, RISKS of cancer; MIRD concerned more with radiopharmaceutical diagnostics/therapy, and now with voxel tomographic models and deterministic effects of dose.

32
Q

Tritium Facts

A

Max E: 0.018MeV, Half-life: 12.3 yrs

33
Q

Dose of non-penetrating radiation to internal organ

A 
D = 19900 * Concentration * E * Teff * (1 - f)
C = MBq/g, E = avg energy, 1-f = fraction decayed
34
Q

Conversion from MeV/g to mGy

A

1.602 x 10^-7 mGy = 1 MeV/g

35
Q

Physical Stage of water in ionizing radiation

A

In this stage, water is either excited or ionized. Occurs in less than 10^-15 second.

36
Q

Prechemical Stage of water in ionizing radiation

A

In this stage:
Excited water: H2O* -> .OH + H. or -> H2O+ + e-
Electron is dissolved: e- -> e- aqueous.
Occurs 10^-15 to 10^-12 second.

37
Q

Chemical Stage of water in ionizing radiation

A

In this stage:
Radicals combine and aqueous electrons attack atoms.
Occurs in 10^-12 to 10^-6 second.
In tissue, the radicals survive for ~0.1 to 1 us.

38
Q

Oxygen Enhancement Ratio (OER)

A

Dose needed to achieve LD50 in hypoxic environment / Dose needed to achieve LD50 in oxygenated environment > 1

39
Q

Diffusion constants for radicals

A

(Multiply by 10^-5 cm^2/s) OH 2; e- 5; H3O+ 8; H 8

40
Q

Dose Modifying Factor (DMF)

A

DMF > 1. Dose to LD50 with radioprotectors / Dose to LD50 without radioprotectors

41
Q

Four types of radiation effect

A

Somatic, hereditary, stochastic, nonstochastic

42
Q

Non-stochastic effects

A

erythema, tissue burns, cataract, sterility, acute radiation syndromes, and death

43
Q

Acute Radiation Syndromes: Hematopoetic Syndrome

A

1Gy or greater to blood. Latent period of 4 weeks. Cause of death: infection, dehydration. Prominent symptom: loss of lymphocytes and neutrophils, and later RBC/platelets.

44
Q

Acute Radiation Syndromes: Gastrointestinal Syndrome

A

> 6~8Gy to GI tract. Latent period of 3-5 days. Cause of death: uncontrolled passage of fluids, infection, electrolyte imbalance, within 4 to 10 days. Prominent symptom: Loss of appetite, ileus (obstruction), nausea & vomiting.

45
Q

Acute Radiation Syndromes: Cerebrovascular Syndrome

A

> 20Gy to brain. Latent period of 12 hrs. Cause of death: brain swelling, inflammation (meningitis). Prominent symptom: disorientation, ataxia (incoordination), burning sensation, loss of consciousness.

46
Q

Sterility non-stochastic dose limits

A

Ovaries: 10 rad, delay of menstruation. 200 rad, temporary sterility. 500 rad, permanent sterility.
Testes: 10 rad, drop in spermatozoa. 200 rad, temporary infertility. 500 rad, permanent infertility.

47
Q

Radium Dial Painters Study

A

Ra-226 (alpha), Ra-228 (beta) used for glow-in-dark watch. ~80rad threshold for bone sarcoma, > 10uCi Radium risky.

48
Q

High BKG (Background Radiation) Area Study

A

Global average is 100 mrem/yr, except radon. Studied Brazil, India, China with higher-than-normal BKG. 640 mrem/yr in Guarapari, Brazil due to monazite containing thorium, uranium. 380 mrem/yr in Kerala coast, India for 70,000 inhabitants. Guangdong, China at 550 mrem/yr for 73,000 people.

49
Q

[ICRP 60, NRC] ICRP Limit on Committed EFFECTIVE Dose (not equivalent) due to ingested radionuclides vs. NRC Limit on Committed EFFECTIVE Dose.

A
50
Q

Derived Air Concentration in Bq/m^3?

A

DAC = ALI(Bq) / 3000m^3 (a person breathes 3000m^3 per year)

51
Q

I-131 production and half-life

A

Produced from Te-131m (half life 30 hrs), and I-131 has half life of 8.05 days

52
Q

Roentgen to C/kg to Dose

A

1 R = 2.58 x 10^-4 C/kg =(multiply by 33.7 J/C of ionization)= 0.877 rad

53
Q

Concept of Dose Equivalent introduced in what ICRP? What is quality Q?

A

ICRP 26. In ICRP 26, Q modifies radiation dose with stopping power. <3.5keV/um = Q = 1; ~7keV/um = Q = 2; 23keV/um = Q = 5 etc. Later replaced by ICRP 60 with w(R), radiation weighting factor.

54
Q

Posting requirements

A

1.00 mSv/hr, high radiation area sign.

55
Q

NRC Regulations: Parts

A

NRC Part 20: protection standards
NRC 10, Part 35: human
NRC 10, Part 71: RAM transport

56
Q

The reference man was originally defined on which ICRP?

A

ICRP 23

57
Q

Which ICRP and what parts established limits for intakes of radionuclides by workers?

A

ICRP 30, parts 2 and addendum on 4

58
Q

Source (S) and target (T) organs defined in which ICRP?

A

ICRP 26

59
Q

Equivalent Dose limit in ICRP 26

A

Lens of eye 150 mSv, all others 500 mSv. Note: this is EQUIVALENT DOSE limit, since it’s for each TISSUE. Remember, H = W(r) * D.

60
Q

Molecules used for ventilation and perfusion lung scan

A

Xe-133 for ventilation, Tc-99m MAA for perfusion

61
Q

Tissues with weight = 0.01 (ICRP 103)

A

skin, bone surface, kidneys, brain, salivary glands

62
Q

Tissues with weight = 0.05 (ICRP 103)

A

bladder, liver, esophagus, thyroid, gonads

63
Q

Tissues with weight = 0.12 (ICRP 103)

A

breast, bone marrow, stomach, colon, lung

64
Q

ICRP 23 was divided into three major parts. What did each of the parts focus on?

A
  1. Anatomical values for reference man; 2. Gross and elemental values for reference man; 3. Physiological data for reference man
65
Q

What proteins with Tc-99m are used in: 1. Skeletal imaging, 2. Liver imaging, 3. Lung perfusion imaging, 4. Kidney-Ureter bladder imaging?

A
  1. Skeletal: Tc-99m diphosphonate
  2. Liver: Tc-99m sulfur colloid
  3. Lung: Tc-99m macroaggregates
  4. Kidney/Ureter: Tc-99m DTPA
66
Q

Identify organs identified as “principal organs” in MIRD “reference man”

A

brain, skull, spine, arm bone, ribs, lungs, heart, liver, kidneys, intestines, bladder, pelvis.

67
Q

MIRD formulation of dose

A

D = A * S(T from S) is absorbed fraction. S(T from S) = sum (delta * AF(T from S) / m_T). And delta = 2.13 * E(MeV) * yield per decay.

68
Q

MIRD Pamphlet No. 21 (2009)

A

Updated internal dosimetry schema and standardized nomenclature.

69
Q

Mo-99 to Tc-99m decay scheme and half-life?

A

Mo-99 decays to Tc-99m via ß- decay, except 14% of the time. Half-lives are 66 hours for Mo-99, 6 hours for Tc-99m.

70
Q

Dose in Gy that will produce cataract

A

> 10 Gy for 100% cataract development. Threshold now 0.5 Gy in 2011 publication on ICRP. Data gathered from MDCT perfusion studies + CSA.

71
Q

Dose in Gy that will produce temporary hair loss

A

3~5 Gy

72
Q

Stratum Basale

A

Stem cells on skin that are most affected by radiation

73
Q

Dose in Gy that will produce erythema

A

300 rad - 1000 rad (3 to 10 Gy)

74
Q

Subclinical < 1 Gy Effects

A

12cGy: sperm count decreases by 45 days
20cGy WHOLE body: dicentric chromosomes appear
75-100cGy: depression in bone marrow

75
Q

Granulocytes

A

“Scavengers,” like macrophages that eat up cells. Neutrophils being one of them.

76
Q

Lymphocytes

A

Secondary immune response cells (antibodies etc)

77
Q

Compartment Model for radioactive intake introduced in what ICRP?

A

ICRP 30

Radiation Protection (4 decks)

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